Method of Forming a Metal Container

ABSTRACT

A method of forming a metal container comprises: narrowing a first top section of the container in at least one narrowing step, wherein after narrowing the first top section, the first top section has a first top section minimum outer diameter; and narrowing a second section of the metal container after narrowing the first top section, wherein after narrowing the second section, the second section has a second section minimum outer diameter; wherein the second section is below the first top section minimum outer diameter and wherein the second section minimum outer diameter is larger than the first top section minimum outer diameter. In some embodiments, the second section is below the first top section minimum outer diameter. In some embodiments, the second section of the metal container is necked with a necking die.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional PatentApplication No. 61/495,640, filed Jun. 10, 2011, which is incorporatedherein by reference in its entirety.

BACKGROUND

Metal containers are mass produced. In order to narrow the tops of themetal containers to accept a closure, often several operations arerequired using several different necking dies to narrow each metalcontainer a desired amount. Even more narrowing steps and necking diesare required to form a metal container into a bottle or other shape morecomplex than a standard beverage can. Sometimes, over 20 or 30 neckingoperations are required to narrow a metal container.

SUMMARY

A method of forming a metal container comprises: narrowing a first topsection of the container in at least one narrowing step, wherein afternarrowing the first top section, the first top section has a first topsection minimum outer diameter; and narrowing a second section of themetal container after narrowing the first top section, wherein afternarrowing the second section, the second section has a second sectionminimum outer diameter; wherein the second section is below the firsttop section minimum outer diameter and wherein the second sectionminimum outer diameter is larger than the first top section minimumouter diameter. In some embodiments, the second section is below thefirst top section minimum outer diameter.

In some embodiments, narrowing the second section of the metal containercomprises necking with a necking die. As used herein, “necking die”refers to any die that can be used to narrow the diameter of any portionof the container including a top necked portion, a shaped portionbeneath the top necked portion and any other portion of the container.In some embodiments, a minimum inner diameter of the working surface ofthe necking die is greater than the first top section minimum outerdiameter. In some embodiments, the step of narrowing a second section ofthe metal container to a second section minimum outer diameter comprisespassing the necking die beyond the first top section minimum outerdiameter.

In some embodiments, the second section is narrowed 5%, 10%, 15%, 20%,25%, 30%, 35%, 40%, 45% or 50% in a single stroke of a necking die.

In some embodiments, a reduction of about 5%, 10%, 15%, 20%, 25%, 30%,35%, 40%, 45% or 50% is possible in a single narrowing step using asingle die.

In some embodiments of the invention, an original diameter of a metalcontainer is narrowed by at least a 5%, 10%, 15%, 20%, 25%, 30%, 35%,40%, 45% or 50% using a single necking die without a knockout and/orwithout first expanding the metal container.

In some embodiments, at least part of the second section is below thefirst top section.

In another embodiment, a method of forming a metal container comprises:narrowing a first top section of the metal container in at least onenarrowing step, wherein the first top section has a first top sectionminimum outer diameter; and narrowing a second section of the metalcontainer to a second section minimum outer diameter after narrowing thefirst top section, wherein the circumference of the first top sectionminimum outer diameter does not change when narrowing the second sectionof the metal container and wherein the second section minimum outerdiameter is larger than the first top section minimum outer diameter. Insome embodiments, the second section may be completely encompassedwithin the first top section.

One embodiment of a method of forming a metal container comprises:narrowing a first top section of the container in at least one narrowingstep, wherein after narrowing the first top section, the first topsection has a first top section minimum circumference; and narrowing asecond section of the metal container after narrowing the first topsection, wherein after narrowing the second section, the second sectionhas a second section minimum circumference; wherein the first topsection minimum circumference does not change when narrowing the secondsection of the metal container and wherein the second section minimumcircumference is larger than the first top section minimumcircumference. In some embodiments, the second section minimumcircumference is below the first top section minimum circumference. Insome embodiments, the second section is completely encompassed withinthe first top section. In some embodiments, at least part of the secondsection is below the first top section. In some embodiments, narrowingthe second section of the metal container comprises necking with anecking die. In some embodiments, necking is performed without the useof a knockout. In some embodiments, a minimum inner circumference of aworking surface of the necking die is greater than the first top sectionminimum outer circumference. In some embodiments, the step of narrowinga second section of the metal container to a second section minimumcircumference comprises passing the necking die beyond the first topsection minimum circumference. In some embodiments, the second sectionis narrowed at least 5% in a single stroke of a necking die. In someembodiments, the second section is narrowed at least 10% in a singlestroke of a necking die. In some embodiments, the second section isnarrowed at least 15% in a single stroke of a necking die.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional side view of a preform metal container.

FIG. 1B is a cross-sectional side view of the preform metal container ofFIG. 1A after having been narrowed and a necking die.

FIG. 2 is a cross-sectional side view of the preform metal container ofFIGS. 1A and 1B after having been narrowed and while being necked withthe necking die of FIG. 1B.

FIG. 3 is a cross-sectional side view of the preform metal container ofFIGS. 1A-2 after having been narrowed and while being necked with thenecking die of FIGS. 1B and 2.

FIG. 4 is a partial cross-sectional side view of a metal containerhaving a chimney and a curl before having undergone the step ofnarrowing a second section of the metal container.

FIG. 5 is a cross-sectional side view of a metal container after havingundergone the step of narrowing a first top section of the metalcontainer.

FIG. 6 is a partial cross-sectional side view of a metal containerhaving a curl before having undergone the step of narrowing a secondsection of the metal container.

FIG. 7 is a partial cross-sectional side view of a necking die,including a working surface, that may be used to narrow a second sectionof the metal container.

FIG. 8 is a cross-sectional side view of a metal container after havingbeen narrowed and a necking die.

FIG. 9 is a cross-sectional side view of the metal container of FIG. 8after a second section has been narrowed.

FIG. 10 is a top view of the metal container shown in FIG. 8.

FIG. 11 is a top view of the metal container shown in FIG. 9.

FIG. 12 is a partial cross-sectional view of a metal container afterhaving undergone narrowing of a first top section and of the necking dieof FIG. 7.

FIG. 13 is a cross-sectional side view of a metal container after havingbeen narrowed.

FIG. 14 is a cross-sectional side view of the metal container of FIG. 13after a second section has been narrowed.

FIG. 15 is a cross-sectional side view of a metal container after havingbeen narrowed and a necking die.

FIG. 16 is a cross-sectional side view of the metal container andnecking die of FIG. 15 while the container is being necked.

FIGS. 17A-17D show an example of a multi-stage necking progressionaccording to one embodiment of the invention.

DESCRIPTION

For the purposes of this specification, terms such as top, bottom,below, above, under, over, etc. are relative to the position of afinished metal container resting on a flat surface, regardless of theorientation of the metal container during manufacturing or forming stepsor processes. A finished metal container is a metal container that willnot undergo additional forming steps before it is used by an endconsumer. In some embodiments, the top of the container has an opening.When the term “diameter” is used with respect to a necking die,“diameter” refers to an inner diameter. When the term “diameter” is usedwith respect to a container, “diameter” refers to an outer diameter.

Referring to FIGS. 1A-3, a method of forming a metal container 20comprises: narrowing a first top section 22 of the metal container 20 inat least one narrowing step, wherein after narrowing the first topsection 22, the first top section 22 has a first top section minimumouter diameter 24; and narrowing a second section 26 of the metalcontainer 20 after narrowing the first top section 22, wherein afternarrowing the second section 26, the second section 26 has a secondsection minimum outer diameter 28, wherein the second section 26 isbelow the first top section minimum outer diameter 24 and wherein thesecond section minimum outer diameter 28 is larger than the first topsection minimum outer diameter 24. Part of the second section 26 isbelow the first top section 22. In some embodiments, the second sectionminimum outer diameter 28 is less than the original diameter 36 of themetal container 20. The original diameter 36 is the diameter of themetal container after it has been formed via drawing and ironing orextrusion but before it has been shaped, i.e. what is commonly known inthe art as a pre-form metal container. Shaping includes necking andexpanding the diameter of the container. In some embodiments, there isno need to pre-stress the metal container 20 by expansion or other meansbefore it is narrowed.

FIG. 1B shows a cross-section of a metal container 20 after havingundergone the step of narrowing a first top section 22 of the metalcontainer. FIG. 1B also shows a cross-section of a working surface of anecking die 32 before contacting the metal container 20. The metalcontainer 20 shown in FIG. 1B is commonly known in the art as a neckedpre-form. FIGS. 2 and 3 show the cross-section of the metal container 20while the second section 26 is being narrowed by a working surface ofthe necking die 32. In FIG. 2, the working surface of the necking die 32is in mid-stroke. In FIG. 3, the working surface of the necking die 32is at the end of its stroke. FIGS. 1B-3 are based on output from finiteelement modeling. In some embodiments, the stroke of the necking die 32extends to the bottom of the metal container 20 or proximate to thebottom of the metal container 20.

The metal comprising the metal container 20 may be any metal known inthe art including, but not limited to, aluminum and steel. The metalcontainer 20 may or may not have a dome. In some embodiments, the metalcontainer 20 is a one-piece metal container having a closed bottom. Insome embodiments, the metal container 20 is comprised of multiple piecesof metal seamed together. In some embodiments, a sidewall of the metalcontainer 20 has a uniform thickness from top to near the bottom of thecontainer. In some embodiments, a sidewall of the metal container 20 hasa non-uniform thickness. In some embodiments, a sidewall of the metalcontainer 20 is tapered so that the thickness of the sidewall is thinnerat the top of the container than the bottom of the container. In someembodiments, the thickness of a sidewall of the metal container 20varies along the height of the sidewall. In some embodiments, thesidewall is thicker at the top of the container than at a lower sidewallportion of the container.

Narrowing the first top section 22 of the metal container 20 can be doneby any means known in the art, including, but not limited to die neckingand spin forming. Necking or spin forming can be performed any way knownin the art, including as described in U.S. Pat. Nos. 4,512,172;4,563,887; 4,774,839; 5,355,710 and 7,726,165.

Narrowing the first top section 22 may be accomplished using traditionalmeans. In some embodiments, several narrowing steps, e.g. 10-30 or moremay be required to narrow a first top section and form the containersshown in FIGS. 1B, 4, 5, 6, 8, 10, 12, 13, 15 and 17A.

In some embodiments, after narrowing, the first top section 22 includesa chimney 30. The chimney 30 has vertical walls and is a top-mostnarrowed cylindrical portion of a metal container. In some embodiments,the chimney 30 comprises the first top section minimum outer diameter24. The chimney 30 may enable the second section 26 to be narrowed moreaggressively, i.e. a larger diameter reduction may be taken in a singlenarrowing step without damaging the metal container, e.g. wrinkling,tearing or collapsing of the metal container. The presence of a chimney30 in some embodiments helps the opening of the metal container 20 tomaintain its round shape throughout the narrowing process and increasesthe hoop strength of the opening. However, even when a chimney ispresent, the opening of the metal container may become out-of-round oroval during subsequent forming operations.

In some embodiments, the chimney 30 has a curl. FIG. 4 shows a partialcross-section of a metal container 110 having a chimney 111 and a curl112. In some embodiments, the step of narrowing a second section of themetal container after narrowing the first top section occurs after achimney and/or a curl has been formed in the metal container.

Some embodiments do not include a chimney. FIG. 5 shows a cross-sectionof a metal container 70 after having undergone the step of narrowing afirst top section 72 of the metal container 70. In this embodiment, themetal container 70 does not have a chimney. The first top sectionminimum outer diameter 74 is at the opening and top edge 76 of the metalcontainer 70. Some embodiments without a chimney include a curl. FIG. 6shows a partial cross-section of a metal container 114 having a curl116.

As shown in FIGS. 2 and 3, narrowing the second section 26 of the metalcontainer 20 can be accomplished using a necking die 32. In someembodiments, after narrowing the first top section 22 a 26% reduction indiameter of a portion of the metal container 20 in a single stroke of anecking die is possible. In other embodiments, a reduction of diameterof a portion of the metal container 20 of about 5%, 10%, 15%, 20%, 25%,30%, 35%, 40%, 45% or 50% is possible in a single stroke of a singledie. Some embodiments of the invention can reduce the diameter of ametal container in one necking stroke an amount that would requiremultiple necking strokes in the prior art. Some embodiments of theinvention enable large diameter reductions using a single die to formwhat is commonly known as a long-necked metal container, significantlyreducing the required number of long-stroke forming operations necessaryto form a metal container having a particular shape.

In some embodiments, the working surface of the necking die 32 has arelief 35 as shown in FIG. 7 and as described in U.S. Pat. No.7,726,165. In other embodiments, no relief is necessary. The presence ofthe relief 35 in the working surface 37 of the necking die 32 enablesmore aggressive reductions of the metal container 20. In someembodiments, the necking die is comprised of tool steel, carbide,ceramic or any other suitable material known in the art.

In some embodiments, the land 33, of the working surface 37 of thenecking die 32 has a surface roughness average (Ra) ranging from morethan or equal to 8 μin to less than or equal to 32 μin, so long as thesurface of the land 33 does not disadvantageously disrupt the aestheticfeatures of a coating on the metal container in a significantlyobservable manner, as described in U.S. Pat. No. 7,726,165. In otherembodiments, the land has an Ra value in the range of 2 μin to 6 μin.The land 33 is the portion of the working surface 37 of the necking die32 having the smallest inner diameter, i.e. the minimum inner diameterof the working surface.

As shown in FIGS. 2 and 3, in some embodiments, the step of narrowing asecond section 26 of the metal container 20 to a second section minimumouter diameter 28 comprises passing a working surface of a necking die32 beyond the first top section minimum outer diameter 24. In someembodiments, the inner diameter of the land 33 of the working surface ofthe necking die 32 used in the step of narrowing the second section 26of the metal container 20 is greater than the first top section minimumouter diameter 24. A knockout does not need to be used when narrowingthe second section 26. A knockout provides a surface for releasing ametal container from a necking die. In some embodiments, a pilot is usedto control a top edge of a metal container. A pilot is a centering toolthat controls movement of the top edge 34. In some embodiments of theinvention, after narrowing the first top section 22, the originaldiameter of a portion of the metal container 20 is narrowed by at least5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50% using a single neckingdie without a knockout and/or without first expanding the metalcontainer.

In another embodiment, a method of forming a metal container 20comprises: narrowing a first top section 22 of the metal container 20 inat least one narrowing step, wherein after narrowing the first topsection 22, the first top section 22 has a first top section minimumcircumference; and narrowing a second section 26 of the metal containerafter narrowing the first top section 22, wherein after narrowing thesecond section 26, the second section 26 has a second section minimumcircumference wherein the first top section minimum circumference doesnot change when narrowing the second section 26 of the metal container20 and wherein the second section minimum circumference is larger thanthe first top section minimum circumference. The circumference is thelength of the outer perimeter of the metal container lying in a planeparallel to a flat surface upon which the metal container is resting onits bottom as measured by a tape measure. In some embodiments, thesecond section may be completely encompassed within the first topsection.

FIG. 8 shows a cross-section of a metal container after the first topsection 152 has been narrowed but before the second section has beennarrowed using the necking die 160. FIG. 9 shows the metal container 150after the second section 156 has been narrowed. The second section 156is completely encompassed within the first top section 152. FIGS. 10 and11 are top down views of the container in FIGS. 8 and 9, respectively.The minimum circumference 154 of the first top section 152 does notchange when the second section 156 is narrowed. The minimumcircumference of the second section resides in a plane 158 and is largerthan the first top section minimum circumference 154.

FIG. 12 shows certain dimensions of a metal container after havingundergone narrowing of the first top section and immediately prior tothe step of narrowing the second section. FIG. 12 also shows a workingsurface 37 of a necking die 32 immediately prior to making contact withthe metal container. FIG. 7 shows certain dimensions of the workingsurface 37 of the necking die 32, which may be used to perform the stepof narrowing the second section of the metal container. A land 33 andundercut 35 are also shown.

Example 1

In a first example, the dimensions shown in FIGS. 7 and 12 are:

A=2.305″, B=0.990″, C=1.710″, D=2.418″ R₁₁=1.995″, R₁₂=1.995″,R₁₃=0.105″ R₂₁=0.050″, R₂₂=1.500″, R₂₃=2.000″

θ₁₁=0°, θ_(1.2)=46.6144°θ₂₁=85.00°, θ₂₂=18.996°, θ₂₃=23.996°

H₁₁=1.5262″, H₁₂=0.12′ H₂₁=1.4234″, H₂₂=0.040″ L₂₁=0.0854″, L₂₂=0.0000″

Throughout this specification, quotation marks after a number designateinches, “A”, “B”, “C” and “D” represent diameters, “R” represents aradius and “H” represents height.

In this first example, the original starting metal container 20 beforethe first narrowing step was a 59 mm diameter pre-form, after narrowingthe first top section 22, the second section 26 of the metal container20 was narrowed 26% using a single working surface of the necking die 32and a single necking stroke. C represents the minimum diameter of theworking surface of the necking die 32. In this example, the necking die32 travelled 3.5 inches down the metal container 20.

In this first example, the metal container was comprised of aluminum3104 alloy, H19 temper and 0.0100″ thick sidewall prior to the firstnecking step. The dimensions in this example were used as input infinite element modeling. The dimensions of FIG. 12 in this first exampleresult in a metal container having the shape shown in FIG. 1B. Afterbeing necked with the working surface of the necking die shown in FIG. 7having the dimensions in this example, the resulting metal containerwould have the shape of the metal container shown in FIG. 3.

Example 2

FIG. 13 shows a second example of a metal container 40 after havingundergone the step of narrowing a first top section 42 of the metalcontainer. The metal container 40 shown in FIG. 13 is commonly known inthe art as a necked pre-form. FIG. 14 shows the metal container 40 afterthe second section 46 has been narrowed. The first top section 42, firsttop section minimum outer diameter 44, second section 46 of the metalcontainer 40, second section minimum outer diameter 48, chimney 50 andtop edge 54 are also shown in FIGS. 13 and 14.

Referring again to FIGS. 7 and 12, the specific dimensions associatedwith the metal container shown in FIGS. 13 and 14 are:

A=2.086, B=1.218, C=1.822″, D=2.288″ R₁₁=1.500, R₁₂=1.500, R₁₃=0.070R₂₁=0.100″, R₂₂5.000″, R₂₃=4.000″

θ₁₁=0, θ₁₂=48.5640

H₁₁1.1770, H₁₂0.125

θ₂₁=90.00°, θ₂₂=9.862°, θ₂₃=9.862°

L₂₁0.0000″, L₂₂=0.0000″ H₂₁=1.6415″, H₂₂=0.040″

In this example, the original circumference of the metal container 40corresponding to diameter A was 6.563″ as measured with a tape measure.The circumference of the metal container 40 at the first top sectionminimum outer diameter 44 was 3.875″ as measured with a tape measure.The second section minimum circumference of the metal container 40 shownin FIG. 14 was 5.781″ as measured with a tape measure. The metalcontainer shown in FIGS. 13 and 14 is comprised of aluminum 3104 alloy,H19 temper and 0.0088″ thick sidewall prior to the first necking step.After narrowing the first top section 42, a portion of the secondsection 46 of the metal container 40 was narrowed approximately 12.7%using a single necking die and a single necking stroke. The originalstarting metal container before the first narrowing step was a 53 mmdiameter pre-form. The metal container shown in FIGS. 13 and 14 wasactually produced using the methods described herein.

Example 3

FIG. 15 shows a third example of a metal container 80 after havingundergone the step of narrowing a first top section 82 of the metalcontainer and a working surface of a necking die 92 before contactingthe metal container. The metal container 80 shown in FIG. 15 is commonlyknown in the art as a necked pre-form. FIG. 16 shows the metal container80 while the second section 86 is being narrowed by the working surfaceof the necking die 92. In FIG. 16, the necking die 92 is at the end ofits stroke. The first top section 82, first top section minimum outerdiameter 84, second section 86 of the metal container 80, second sectionminimum outer diameter 88, chimney 90, top edge 94 and original diameter96 are also shown in FIGS. 15 and 16.

Referring again to FIGS. 7 and 12, the specific dimensions associatedwith the metal container shown in FIGS. 15 and 16 are:

A=2.305″, B=0.990″, C=1.937″, D=2.430′ R₁₁1.995″, R₁₂=1.995, R₁₃=0.105″R₂₁=0.050″, R₂₂=3.050″, R₂₃=1.000″

θ₁₁=0°, θ₁₂=46.6144°θ₂₁=85.00, θ₂₂=12.573, θ₂₃=17.573°

H₁₁1.5262″, H₁₂=0.125″ H₂₁=1.2228″, H₂₂=0.040″ L₂₁=0.2210″, L₂₂=0.0000″

The metal container shown in FIGS. 15 and 16 is comprised of aluminum3104 alloy, H19 temper and 0.0100″ thick sidewall prior to the firstnecking step. After the first top section 82 was narrowed, a portion ofthe diameter of the second section 86 of the metal container 80 wasnarrowed approximately 16% using a single necking die and a singlenecking stroke. The original starting metal container before the firstnarrowing step was a 59 mm diameter pre-form. FIGS. 15 and 16 wereproduced using finite element modeling.

Example 4

FIGS. 17A-17D show an example of a multi-stage necking progressionaccording to one embodiment of the invention, which includes additionalnarrowing steps after a second section 132 of a metal container 130 isnarrowed. In this fourth example, after the first top section 134 wasnarrowed, a portion of the diameter of the second section 132 isnarrowed so that the diameter is reduced 26% from the original diameter144 in a single necking stroke using a single necking die, resulting inthe container shown in FIG. 17B. The second section 132 is narrowed asecond time via die necking, reducing the diameter of the metalcontainer a total of 36% from the original diameter 144 in a portion ofthe second section 132, as shown in FIG. 17C. The second section 132 isnarrowed a third time via die necking reducing the diameter of the metalcontainer 130 a total of 40% from the original diameter 144 in a portionof the second section 132, as shown in FIG. 17D. FIGS. 17A-17D also showa first top section 134, first top section minimum outer diameter 136,chimney 140, and a top edge 142. A second section minimum outer diameter138 can be seen in FIG. 17B. FIGS. 17A-17D were produced based on outputfrom finite element modeling.

Referring again to FIGS. 7 and 12, data ranges in which it is currentlythought would yield a metal container according to some embodiments ofthe invention when the metal container before the first narrowing stepcomprises a 45 mm-87 mm diameter pre-form, including, but not limitedto, 45 mm (112), 53 mm (202), 59 mm (205), 60 mm (206), 63 mm (207.5),68 mm (211), 73 mm (214), 76 mm (300), 87 mm (307) diameter pre-forms,include but are not limited to:

1.772″≦A≦3.438″ 0.500″≦B≦A 0.7*A≦C≦A R₁₁≧0.125″ R₁₁≦R₁₂≦∞0.100″≦R₁₃≦5.000″ 0.100″≦R₂₃≦10.000″

10°≦θ₁₁≦60°θ₁₁≦θ₁₂≦90°

0<H₁₂<3.000″ 0≦H₂₂≦8.000″

In some embodiments of the invention, the following data ranges areapplicable: 45 mm≦A≦87 mm; 45 mm≦A≦76 mm; 45 mm≦A≦68 mm; 54 mm≦A≦87 mm;54 mm≦A≦68 mm; 76 mm≦A≦87 mm; or 53 mm≦A≦68 mm

18 mm≦B≦28 mm; 2.0″≦B≦3.0″; 2.5:≦B≦3.0″; 18 mm≦B≦43 mm; 25.4 mm≦B≦38 mm;or 26 mm≦B≦33 mm

R₁₁>0.125″, 0.250″, 0.400″, 0.500″, 1.000″ or 5.000″

0.100″≦R₁₃≦0.500″; 0.100″≦R₁₃≦5.000″; 0.250″≦R₁₃≦2.50″;0.250″≦R₁₃≦0.500″; 0.250″≦R₁₃≦0.750″; 0.500″≦R₁₃≦1.00″;0.750″≦R₁₃≦5.000″; or 0.750″≦R₁₃≦2.50″0.100″≦R₂₃≦0.500″; 0.100″≦R₂₃≦5.000″; 0.250″≦R₂₃≦2.50″;0.250″≦R₂₃≦0.500″; 0.250″≦R₂₃≦0.750″; 0.500″≦R₂₃≦1.00″;0.750″≦R₂₃≦5.000″; or 0.750″≦R₂₃≦2.50″0<H₁₂<3.000″; 0.010″<H₁₂<1.00″; 0.010″<H₁₂<5.0″; 0.010″<H₁₂<10.0″;0.025″<H₁₂<0.250″; 0.025″<H₁₂<1.00″; 0.050″<H₁₂<1.00″; or0.010″<H₁₂<0.05″0≦H₂₂≦3.000″; 0.010≦H₂₂≦1.00″; 0.010″≦H₂₂≦5.0″; 0.010″≦H₂₂≦10.0″;0.025″≦H₂₂≦0.250″; 0.025″≦H₂₂≦1.00″; 0.050″≦H₂₂≦1.00″; or0.010≦H₂₂≦0.05″

Ranges of functional dimensions likely depend on many factors including,but not limited to: the type of metal comprising the metal container,including the specific alloy used, the thickness and temper of the metaland the size of the metal container.

Embodiments of the invention are also applicable to other types andsizes of metal containers. For example, some embodiments of theinvention may be used to form metal beverage, aerosol and/or foodcontainers.

While various embodiments of the present disclosure have been describedin detail, it is apparent that modifications and adaptations of thoseembodiments will occur to those skilled in the art. However, it is to beexpressly understood that such modifications and adaptations are withinthe spirit and scope of the present disclosure.

All features disclosed in the specification, including the claims,abstracts, and drawings, and all the steps in any method or processdisclosed, may be combined in any combination, except combinations whereat least some of such features and/or steps are mutually exclusive. Eachfeature disclosed in the specification, including the claims, abstract,and drawings, can be replaced by alternative features serving the same,equivalent or similar purpose, unless expressly stated otherwise. Thus,unless expressly stated otherwise, each feature disclosed is one exampleonly of a generic series of equivalent or similar features.

Any element in a claim that does not explicitly state “means” forperforming a specified function or “step” for performing a specifiedfunction should not be interpreted as a “means or step for” clause asspecified in 35 U.S.C. §112.

1. A method of forming a metal container comprising: narrowing a firsttop section of the container in at least one narrowing step, whereinafter narrowing the first top section, the first top section has a firsttop section minimum outer diameter; and narrowing a second section ofthe metal container after narrowing the first top section, wherein afternarrowing the second section, the second section has a second sectionminimum outer diameter; wherein the second section is below the firsttop section minimum outer diameter; wherein the second section minimumouter diameter is larger than the first top section minimum diameter. 2.The method of claim 1 wherein narrowing the second section of the metalcontainer comprises necking with a necking die.
 3. The method of claim 2wherein necking is performed without the use of a knockout.
 4. Themethod of claim 2 wherein a minimum inner diameter of a working surfaceof the necking die is greater than the first top section minimum outerdiameter.
 5. The method of claim 2 wherein the step of narrowing asecond section of the metal container to a second section minimum outerdiameter comprises passing the necking die beyond the first top sectionminimum outer diameter.
 6. The method of claim 1 wherein the secondsection is narrowed at least 5% in a single stroke of a necking die. 7.The method of claim 1 wherein the second section is narrowed at least10% in a single stroke of a necking die.
 8. The method of claim 1wherein the second section is narrowed at least 15% in a single strokeof a necking die.
 9. The method of claim 1 wherein at least part of thesecond section is below the first top section.
 10. A method of forming ametal container comprising: narrowing a first top section of thecontainer in at least one narrowing step, wherein after narrowing thefirst top section, the first top section has a first top section minimumcircumference; and narrowing a second section of the metal containerafter narrowing the first top section, wherein after narrowing thesecond section, the second section has a second section minimumcircumference; wherein the first top section minimum circumference doesnot change when narrowing the second section of the metal container andwherein the second section minimum circumference is larger than thefirst top section minimum circumference.
 11. The method of claim 10wherein the second section minimum circumference is below the first topsection minimum circumference.
 12. The method of claim 10 wherein thesecond section is completely encompassed within the first top section.13. The method of claim 10 wherein at least part of the second sectionis below the first top section.
 14. The method of claim 10 whereinnarrowing the second section of the metal container comprises neckingwith a necking die.
 15. The method of claim 14 wherein necking isperformed without the use of a knockout.
 16. The method of claim 14wherein a minimum circumference of a working surface of the necking dieis greater than the first top section minimum circumference.
 17. Themethod of claim 14 wherein the step of narrowing a second section of themetal container to a second section minimum circumference comprisespassing the necking die beyond the first top section minimumcircumference.
 18. The method of claim 10 wherein the second section isnarrowed at least 5% in a single stroke of a necking die.
 19. The methodof claim 10 wherein the second section is narrowed at least 10% in asingle stroke of a necking die.
 20. The method of claim 10 wherein thesecond section is narrowed at least 15% in a single stroke of a neckingdie.